Apparatus and method for sanitizing



Nov. 13, 194 w. MALLMANN ET 'AL 2,388,753

APPARATUS AND METHOD FOR SANITIZING Filed Aug. 2. 1939 I N VENTORS Z.Mailman/z Clifford if. Kain lathard 1567462 ra/fer- ATTORNEY5 PatentedNov. 13, 1945 s PATENT "OFFICE r METHOD FOR SANIT'I'ZING Walter LMallmann, East Lansing, and Clifford H. Kain and Richard 'J.'SchaeferjDetroit,

' "assignors to sanozan CorpofzttionjDetro' t, Mich, a corporation ofMichigan Application August 2, 1939, Serial No. 288,030

H '5"Claims. invention terates to an apparatus and niiithdd rer sanitizfg withhzohekaiid other'disinfecting gases erliqilids. 1 I *It s theobject t; this in'ven-tionto produce a cheap and reliably eitect'eAautomatieappata-tus a-nd -methed fo'r sizing all types of-arti'les"anki i n fiase ai ti cies ai e used the J i ng anetransportation of Aid-iii ahdse'lidfo ods such as cussingestin 'aiid Wrinsing utensils. -'I'-l 1isol oj'ect is achieved -bysli bjetihg thearticle te Watersolution -=oi d'ztii-ie vf sll ifieierltcoflcentrationto efiet germi:

" 'didal tion. I

lz'he 'e-rm sanitized -is'- used herein to desigaate the killing ofbacteria, particularly ihaimrul bacteria, and is synonymous with themore commoh riieaning of the term sterilize'd.

invention also contemplates a hovel metnoa aau apparatus :foreile'ctively 'and cheapiy prouucing a saturated water solution .of

ozone.

-ln'tlie drawing: 7 Fig.-1*is a layout of theapparatus. Fig. 2 is a'section throug-h the i duetor fon-dissolving theozone inthewater.

F-ig's. 3 1 through 6 I are detail "views set severalarts-ofthe'induetor. Q

Fig. '7 is a-anodiiied formshowing the injector nozzle positioned abovethe liquid level "an-d in- "cliri'ed to-inziect the ozon'ated streamdownwardly 'intothe' body of water. 7

This invention contemplates the sterilization of "water aind 'of alltypes'o'f ar ticles through iis'eo'fozo'rie. ln thesan itizati'o-n 'o'farticles such, for example, as eatingand drinking utensils,=1' t ispr'oposed to bring the bacteria intoiinti'rhatew tact with the watersolution loi ozo-ne of sutfieienticoncentration toseffect a; germicidalaction. n saturated aqueous solution of ozone is ipreferred' ibut notnecessary. 01f the .article "earn-cm of soil such as-dil,-grease,organic shatter "or other interferingsubstanc'e's upon it, i atersolution of ozone cannot reachthe bac't' m te-destroy the s'arhe. ofnecessity, requires-that the=article be rendered 'fre'e of suchseeders-peer to sanitization by the water solution ofoz'one. Further,for the purpose of :b-ringin'g' the -ar tiole to be sanitized in tointimate contact "with a 1 water -sol-ution of ozone, it isproposed-tosses a- 'contaiiner preferably in the form or tank- I Whichis..-partially filled with -a Satl1- rated wat'er solution 2 of ozone ofsufficient volumeanu depth to permit com lete iinmersion ther n of theartiole to be sanitized. Since Warm Waterhas a ver mw retention ofozone, it is preferable to i operate' this apparatus "at roomtemperature or lower, hence a col' itinuous replenished flow ofozon'ated tap water is desirable. I-liis cbntiriuous iiitroductioir ofozon'ated "water provides suliicient dilution or the c'ontaniinatingsubstances introduced with the articles to be sanitized, so that theelimination :of this :waste by dilution facilitates the easy.maintenance :of the saturated ozone solution by the .minimum dosage ofozone. The level .of the water solution 2 of ozone is maintained:bytheoverfiowipipe. 3 with which theitank l is provided. 1

It is difilcult to obtain a saturated water solution of ozone. However,the instant invention contemplates an apparatus and method by means ofwhich a constantly saturated water solution of ozone can, if desired, beproduced and-maintained. This is achieved by bringing theozone intointimate contact with allthe water "at'the time the ozone is being.diffused or dispersed into the water. For :achieving this result-aninductor, shown in section, .Fig. 2, is used. This inductor comprises ahousing '4 which is connected by pipe '5 to 'a source of waterund'erypressure. Thezfiow of water through the line 5 is controlled bythe hand operated valve 6. The 'housing-d-isalso connected with a sourceof ozone bythe tube 1. The housing 4 is provided with a nozzle 8 havinga smallxoutlet orifice 9 throughwhich the water from line 5 underpressure is discharged in a very small stream. The housing 4 is alsoprovided with a nozzle Ii] spaced .from' nozzle .8 toapro- 'vide achamber 45. The nozzle it is provided with an orifice lZslightly largerthan orifice 9 and axiall aligned with orifice 9.

The ozone may be generated in any suitable ozone generating cell. Ashereinshown, tube 1 is connected with an ozone generating cellcomprising an inside electrode 63 in the form-of a cylinder, an outsideelectrode 15 positioned over and spaced as at M from the inner electrode13, and a glass dielectric tube l6 positioned between the inside andoutside electrodes. The joint between the inside electrode and the glassand the outside electrode is sealed by suitable insulating material H.The wires Wand t9 leading to the secondary winding 20 of a transformerare connected respectively to the inner and outer electrodes. Theprimary winding 2| 0f the transformer is connected with electric powerlines 22 and 23 leading from a source of current of any suitable voltagesuch as the ordinary volt domestic electric power line. The transformerpreferably steps up the voltage in the secondary to several thousandvolts, that is, sufilciently high to generate ozone in the ozonegenerating cell.

It isrdesirable. to have'the ozone generatingcell fgenerate ozonefionlywhen needed. To this end th :air inlet tube-24 is connected to thehousing 25 0f a vacuum switch actuator. Aifiexible.diaphragm==26:isypositioned in the housin 25. The diaphragmwfi isbacked up by the compression spring 121, the compression of which: isvaried by :t 5 1-, sscrew 28. The :inside of the housing 2 6 :is s opento atmosphere throughopening 29. A t

switch comprising contacts and 3| is positioned in line 23. The contacts30 and 3| are normally out of contact. Upper contact 3| is controlled byplunger 32 which is connected to diaphragm 26.

It will be readily seen that when a vacuum is created in suction line 1by the Venturi action of the water flowing through the inductor 4, a

partial vacuum-is set up in the chamber 33 below the diaphragm 26. Asthis partialvacuum is created in chamber 33 the diaphragm 26 is drawndown and the pin 32 in turn makes a contact between terminals 30 and 3|of the momentary contact switch. The momentary contact switch is knownas a micrometic switch which has the advantage of making and breakinwith a very' slight movement of the actuating pin and the break and makeis very positive and requires but little pressure on the pin. Whencontact is made between terminals 30 and 3| the electric circuit iscompleted through the primary H of the trans former and a high potentialis created in the secondary 20 of the transformer which is in circuitwith the electrodes l3 and I5 of the ozone gengenerating cell, whichozone is drawn into the water passing through inductor 4 and dischargedinto the tank through orifice [2. The ozone discharged into the tank isthoroughly mixed with the water due to the inducting effect by skinfriction and expansion of the small diameter stream which is projectedfrom the nozzle through the suction chamber, and as this small stream isfurther projected into the body of water in the tank, agitation andadditional diffusion is obtained by the spray effect set up by the resistance of the tank water.

To prevent water from backing up into the suction line I in case theorifice I2 is stopped, an

automatic shut off valve is provided. This valve I consists of a float35 which is preferably turned out of aluminum or other light metal. Thefloat 35 is in the nature of a thimble encompassing a chamber 36 open atits lower end as at 37. The lower end of the float is provided with acircumferential flange 38 provided with four radial grooves 39. Theinductor is located in the tank I in vertical position, as shown inFigs. 1 and 2, so that the float 35 can be positioned vertically asshown in these figures with the flange 38 down and the body portion ofthe float guided by the serrated wall 40 of the base 4! in member 42.The lower face 43 0f the member 42 serves as a seat against which theupper face 44 of the float 36 seats to prevent flowing of water in theline I.

Since the bottom side of the float is open and at all times filled withair due to the fact that the suction created by the inductor draws allthe water from suction line I and chamber 45 which surrounds nozzle 8,in the case the outlet orifice I2 is stopped and water pressure is builtup in the cavity 45, the water is forced into the ozone inlet 46.However, as water enters ozone inlet 46, the float valve 35 rises andthe flange 44 seats against seat 43 thus closing off the serrations 40and preventing water from flowing into the suction line I,

In normal operation when the orifice I2 is not stopped the float 35rests upon seat and the ozonated air passes from line 1 through chamber36, about valve 35, through radial grooves I 39, and thence throughoutlet 45 into mixing chamber 45.

In a practical working apparatus the ozonewater mixing device wasoperated under the following conditions: The static city water pressurein the line '5 was 23 /2 pounds per square inch which is equal to a headof 54 feet. The

critical diameter of the orifice 9, which was found to give the bestresults, was .050 inch. This size orifice gave a good vacuum, and anexcellent diffusion of the ozone in the water 2 of the tank. Orifice I!was .080 inch, The outlet end of orifice 9 was spaced %4 of an inch fromthe inner end of orifice [2. The flow through orifice 9 was .45 gallonper minute. In using this size orifice the reduction in pressure inwater line 5 amounted to approximately one pound or .04 of the totalpressure, Larger orifices created quite a substantial reduction in thedynamic pressure of the water flowing through line 5. However, theamount of water passing through the orifice 9 remains practically thesame over quite a wide range of pressures so that variations in thestatic water pressure in line 5 is not a critical consideration. 7

It will be noted that the mixingdevice 4 is preferably positioned inthe'water 2 so that the orifices l2 and 9 are beneath the upper surfaceof the water or just above the surface thereof and in close proximitythereto, so that the discharge fiows into the water, thereby creating aspray effect and agitating the tank water, an excellent mixture beingobtained as the water and ozonated air is projected with high velocityout of orifice I2. In effect an emulsion of ozonated air and water iscreated adjacent the orifice I2 and beneath the surface of, and withinthe body of, water 2. This emulsion changes into a solution. The ozonebubbles created by mixture 4 are so small that they do not lift out ofthe water 2 but are taken into solution up to the point of saturation.In order to maintain the body of water 2 saturated with ozone preferablythe ozonator above described is run continuously so that a fresh supplyof intermixed ozone and water is constantl flowing through mixer 4 andorifice l2 into the body of water 2. The overflow passes out of tank Ithrough overflow 3. The output of the ozone creating cel1 is, of course,corelated with the volume of water passing through pipe line 5 and outof orifice l2 so that a saturated water solution of ozone is obtained.The projecting of a small stream of ozone and water at a rapid speedthrough orifice 12 into the larger body of water 2 is an importantfactor in getting the ozone into solution in the body of water 2 andpreventing the same from rising to the surface of the body of water andthence passing into the air, however, the amount of ozone is purposelyproduced in excess of the amount required to maintain a saturatedsolution in the tank, an the excess rises to the surface and permeatesthe surrounding atmosphere and has the desirable effect of destroyingodors such as those produced by stale beer, smoke and food.

Preparatory to sanitizing an article, such as a cooking, eating ordrinking utensil, the article is first washed to remove the soil, ifany, and then immersed in the saturated water solution of ozone 2 asuflicient length of time to kill the micro-organisms. In numerous testsit has been demonstrated that micro-organisms have been killed at a veryrapid rate. Set forth below are protocols of experiments made with theabove described sanitizing apparatus. Two cultures were used, namely,Staphylococcus aureus and Escherichia coli, which are representativetypes of organisms used for measuring germicidal efllciency. The factthat in these laboratory tests it was possible to kill these organismsin the large numbers tested indicates the effectiveness of thisapparatus in actual practice, The actual killing time is equal to, oreven less than, that obtained with equivalent amounts of chlorine. Inthe case of chlorine it is customary to carry a high residual to carefor the introduction of soil and micro-organisms over a considerableperiod of time due to the customary method of intermittent dosing,although the actual amount needed to effect killing is comparable tothat for ozone. The continuous introduction of ozone into the body ofwater 2 makes possible the carrying of a lethal dose which compensatesfor the lack of a high residual.

Test organism-Escherichia coli.

Capacity of tank-12,500 ml.

Rate of fiow into tank during test runs-1,000

ml. per second interval.

Number of organisms in tank before adding inoculum per ml.

Number of Escherichia coli added at start of test-300,000 per ml.

Concentration of ozone: approximately .2 part per million parts of waterby weight.

Test organism--Staphylococcus aureus.

Capacity of tank-42,500 ml.

Rate of fiow into tank during test runs-1,000

ml. per 20 second interval.

Number of organisms in tank before adding inoculum-0 per ml.

Number of Staphylococcus aureus added at start of test-320,000 per ml.

Number of organisms surviving per ml.

Time of exposure in seconds Concentration of ozone: approximately .2part per million parts of water by weight.

We claim:

. 1. The method of sanitizing an article comprising the steps ofimmersing the article in a flowing water solution of ozone andcontinuously adding fresh ozonated water to the solution andcontinuously withdrawing a portion of the used solution in amountscommensurate with the input of fresh ozonated water.

2. Sanitizing apparatus comprising a tank adapted to receive the articleto be sanitized and adapted to receive a water solution of ozone, asource of ozone, a source of water, a mixing nozzle positioned in thetank below the level of the said solution, means connecting the saidnozzle with the source of ozone and with the source of water underpressure, the said nozzle having a small orifice opening directly intosaid tank whereby a small, fast moving stream of water and ozone can beprojected directly into the water solution below the level thereof, andmeans positioned remote from the said nozzle for continuously removingsome of the solution from the tank.

3. Sanitizing apparatus whereby an article to be sanitized can beimmersed in a Water solution of ozone comprising a tank adapted toreceive a water solution of ozone, an aspirating nozzle positionedwithin said tank beneath the solution level, means for connecting saidaspirating nozzle with a source of water under pressure, and a source ofozone whereby as the water is projected through and out of the saidnozzle the ozone is drawn into the nozzle and then projected with thewater directly into the solution in a fine jet whereby the ozone isdissolved in the said water solution, and outlet means for the said tankfor removing some of the water solution of the ozone.

4. Sanitizing apparatus whereby an article to be sanitized can beimmersed in a water solution of ozone comprising a tank adapted toreceive a water solution of ozone, an inductor positioned within thetank below the solution level, said in- I ductor having a passagewaytherein, a nozzle positioned in said passageway and connected with asource of water under pressure, a nozzle positioned in said passagewayand spaced from the first mentioned nozzle, the orifices of the saidnozzles being in alignment with each other, the orifice of said secondnozzle opening directly into the tank below the solution level, an inletinto the said passageway between the two nozzles, a source of ozoneconnected to said inlet whereby, as the water flows out of the firstnozzle and an aspirating efiect is created thereby, the ozone is drawninto said passageway between said nozzles and water and ozone are forcedthrough the said second nozzle directly into the solution in said tankbeneath the solution level, and means for maintaining the water solutionof ozone within the tank at an approximately constant level.

5. A method for sanitizing articles at room temperature or belowcomprising the steps of first cleansing the article of soil such asgrease, oil, or other organic matter, and then immersing the article ina liquid water solution of ozone at room temperature or below for aperiod of time sufficient to kill the bacteria or germs carried by thearticle, and continuously replenishing the water solution of ozone witha water solution of ozone at room temperature or below.

WALTER L. MALLMANN. CLIFFORD H. KAIN. RICHARD J. SCI-IAEFER.

